How to Find and Fix Wi-Fi Dead Zones

A dead zone is almost always one of four things: distance, a dense wall, a badly placed router, or a channel your neighbors are already sitting on. Work out which one before you buy anything. Two of the four are free to fix, and buying a mesh system to solve a router that is sitting in a cupboard behind a boiler is an expensive way to not fix the problem.

What a dead zone actually is

Your router broadcasts on two or three frequency bands at once. The 2.4 GHz band travels furthest and gets through walls best, but it is slow and crowded. The 5 GHz band is several times faster and much less crowded, but the higher the frequency, the worse it survives anything solid. The 6 GHz band on newer hardware is faster again and worse again at getting through things.

That trade-off is the whole story. A dead zone is a place where the fast band has already died and the slow band is either too weak to be useful or too congested to carry anything. Your phone reports "connected" because it can still hear the router. It just cannot have a usable conversation with it.

This is why a dead zone often behaves inconsistently. A page loads, a video call drops, a smart speaker works but a laptop does not. Different devices have different antennas and different tolerance for a marginal link, so they fail at slightly different distances.

The four real causes

1. Distance from the router

The most common cause and the most boring. Signal strength falls off sharply with distance even through open air, so a single router in a corner of a long house will always disappoint at the far end. If your dead zone is simply the room furthest from the router, you have found your answer.

2. Something dense in the way

Not all walls are equal, and this is the part most guides skip. A single sheet of drywall costs you very little. Brick, concrete, stone and tile cost you a great deal. Anything with metal in it — foil-backed insulation, plaster on metal lath, a metal-framed mirror, a fridge, a filing cabinet, ductwork — is far worse than its thickness suggests, because metal reflects radio energy rather than letting it pass. Water is also a strong absorber, which is why a large aquarium, a hot water tank or even a full bath can create a shadow.

The ranking below is the rule of thumb, not a measurement — the real figure depends on the exact material and its thickness. Treat it as an ordering, and use it to work out which wall to suspect.

3. The router is in the wrong place

Routers get installed where the cable enters the house, which is almost never where the house needs coverage from. A router in a corner is broadcasting half its coverage into next door's garden. A router on the floor is fighting through every piece of furniture in the room. A router in a media cabinet with a games console and an amplifier is sitting in a metal box. This is free to fix and it is the single most underrated change you can make. There is a whole page on it: where to put your router.

4. Congestion, not weakness

In an apartment building or a dense street, the 2.4 GHz band may have a dozen networks fighting over three non-overlapping channels. Your signal is strong and still unusable, because your router keeps having to wait its turn. The tell is that the problem gets worse in the evening and is fine at 7am. That is a different problem with a different fix, covered in Wi-Fi interference and Wi-Fi that slows down at night.

How to find your dead zones, room by room

Do this before you buy anything. It takes about fifteen minutes and it will tell you whether you need one extender or a whole system.

1. Pick one device and use only that device. A phone is fine. Comparing a laptop in one room to a tablet in another tells you about the devices, not the house.
2. Stand next to the router and run a speed test. Write the number down. This is your ceiling. Nothing in the house will beat it.
3. Repeat in every room, at the height you actually use the device. Sitting on the sofa, at the desk, in bed. Not standing in the doorway holding the phone up.
4. Write down the signal strength as well as the speed. On Android, a Wi-Fi analyzer app shows it in dBm. On iOS, Apple's own AirPort Utility can show signal strength once you enable its Wi-Fi scanner in Settings. Roughly: −50 dBm is excellent, −67 dBm is the floor for reliable video calling, −75 dBm and below is a dead zone even if it says "connected".
5. Note where the speed falls off a cliff rather than tapering. A gradual decline as you walk away is distance. A sudden collapse between two adjacent rooms is a wall, and now you know which wall.

If you would rather see this as a picture than a list of numbers, the heatmap apps do exactly that and one of them is free: map your dead zones with a heatmap app.

How to tell which cause is yours

Take the numbers from the walkaround and match them against this. This is the step almost nobody writes down, and it is the one that stops you buying the wrong thing.

Fixes, cheapest first

Work down this list in order. Every item above the line costs nothing, and between them they solve a genuine share of the dead zones people spend money on.

1. Move the router toward the middle of the house and up off the floor. Central, high, out in the open. A shelf beats a sideboard; a sideboard beats the floor; anything beats a cupboard.
2. Get it out of the media cabinet. Metal enclosures and a stack of other electronics are a genuinely bad environment for a radio.
3. Point the antennas properly, if it has them. For a single-story house, vertical. For coverage on the floor above, angle some of them outward — the radiation pattern is a doughnut around the antenna, not a beam along it, so a vertical antenna covers sideways well and upward badly.
4. Split the bands, or stop splitting them. If your router presents one network name for both bands and a specific device keeps clinging to the slow one in a good room, giving the 5 GHz band its own name lets you pin that device to it. If devices are dropping as they move around, a single merged name usually roams better.
5. Change the 2.4 GHz channel to 1, 6 or 11. Those are the only three that do not overlap in the US. Pick whichever your loudest neighbor is not using.
6. Update the firmware. Unglamorous, occasionally transformative.
7. Turn off the smart-band-steering feature if devices keep sticking to the wrong band. It is well-intentioned and on some hardware it is worse than nothing.

If the dead zone survives all seven, it is real and physical, and now you are choosing hardware with a clear idea of what the hardware has to do.

If you do need hardware

There are three shapes of answer, and the right one follows directly from what you measured.

• One bad room, and only one. A single extender, placed roughly halfway between the router and the bad room, in a spot that still has a decent signal. Cheap, and adequate for browsing and video. The catch is real and we cover it in mesh Wi-Fi versus an extender: a wireless extender talks to your router and to your laptop using the same radio, so it roughly halves the throughput it passes on.
• Several rooms, or a whole floor. A mesh system. Size it by your square footage rather than by the coverage number on the box, and prioritize a system with a dedicated band for the nodes to talk on — backhaul is the detail that decides everything.
• You can run one Ethernet cable. Then do that, and the whole problem changes character. A wired access point, or a mesh node with a wired backhaul, has none of the throughput penalty above. If pulling cable is impossible, your house's existing coax or electrical wiring may be able to stand in — see powerline adapters.

Our three picks below cover those three shapes. The first is the default for a genuine coverage problem, the second is the cheap single-room fix, and the third is what to buy when you would rather pay for the problem to go away than tune anything.

The three mistakes people make

Buying a mesh system for a congestion problem. If your signal is strong and your speeds are bad, more access points will make the congestion slightly worse, not better. Diagnose first.

Putting the extender in the dead zone. An extender can only rebroadcast what it receives. In the dead zone it receives almost nothing and rebroadcasts almost nothing, at full strength, which feels like it should work and does not. It goes halfway.

Assuming a faster internet plan will help. If the room is getting 15 Mbps out of a 300 Mbps plan, upgrading to 600 changes nothing, because the bottleneck is the last thirty feet inside your house. Check what you actually need before you pay more: do you need a new router?